Boeing has presented the U.S. Air Force with design options for America’s next intercontinental ballistic missile (ICBM), the Ground Based Strategic Deterrent (GBSD).

The review marks the achievement of a key contract milestone.

“We offered the Air Force cost and performance trades for a deterrent that will address emerging and future threats. By considering the various capabilities and opportunities for cost savings, the Air Force can prioritize system requirements as we progress toward the program’s next phase,” said Frank McCall, Vice President, Boeing Strategic Deterrence Systems.

The Air Force awarded Boeing a $349 million contract in August to mature the GBSD weapon system design. Boeing completed a system requirements review in November. A system functional review will occur later this year, and Boeing will present its preliminary design review to the Air Force in 2020.

Designed to serve as a reliable deterrent to nuclear threats over the next 50-plus years, the GBSD weapon system will begin to replace the Minuteman III ICBM in the late 2020s.